Construction of tubular assemblies

ABSTRACT

A method and apparatus for constructing a tubular assembly  40  comprising an inner portion ( 24 ) and a further portion ( 23 ) surrounding the inner portion. The inner portion ( 24 ) comprises reinforcement ( 37 ) and the further portion ( 23 ) being formed from a strip ( 50 ) of material comprising two opposed longitudinal marginal side portions ( 53 ). The apparatus comprises an assembly station ( 220 ) comprising a wall ( 253 ). The apparatus comprises means for advancing the inner portion ( 21 ) along a first path ( 231 ) extending passed the wall ( 253 ), and means for advancing the strip ( 50 ) along a second path ( 232 ) and causing the strip to encircle the wall ( 253 ) and thereby wrap about and surround the inner portion ( 21 ). The apparatus further comprises means ( 321 ) for introducing resinous binder into the reinforcement ( 37 ) as the strip ( 50 ) is being wrapped about the inner portion ( 21 ).

TECHNICAL FIELD

This invention relates to elongate hollow structures of compositeconstruction, including in particular tubular structures. Moreparticularly, the invention is concerned with the construction of atubular assembly used in the production of tubular structures.

While the inventions has been devised particularly in relation to theproduction of tubular structures in the form of pipes, it may also beapplicable to the production of other elongate hollow elements,including for example tubular elements (such as ducts and tubes),tubular structural elements (such as shafts, beams and columns), andother tubular elements of composite construction.

BACKGROUND ART

The following discussion of the background art is intended to facilitatean understanding of the present invention only. The discussion is not anacknowledgement or admission that any of the material referred to is orwas part of the common general knowledge as at the priority date of theapplication.

The discussion is provided in the context of the construction of tubularstructures in the form of pipes, although the invention may haveapplication to other elongate hollow structures of compositeconstruction, as would be understood by a person skilled in the art.

It is known to construct pipes using fibre-reinforced plasticcomposites. Typically, such pipes are constructed by a process in whichrovings of filaments of fibre material, (such as glass fibres) areimpregnated with a thermosettable resin or thermoplastic composition andwound back and forth on a mandrel to form a pipe wall structure ofcomposite construction. The pipes are then joined together in the fieldwith rubber adhesive or wrapped fibreglass joints to form a pipeline.

Further, there have been attempts to produce a continuous pipe bypultrusion, involving a wet body of reinforcement fibres being drawnthrough a heated mould to cure the pipe and the pipe then wound onto aspool. Pipes constructed in this way are typically limited to lengths ofabout 1 km and diameters of about 100 mm

Typically, such pipes are required to bear both hoop and axial stresses,and the construction can be a compromise between the hoop and axialstress bearing properties required for the pipe. Hoop strength can beoptimised by winding the reinforcing filaments at an angle approaching90° to the pipe axis. Axial strength can be optimised by winding thereinforcing filaments at an angle approaching the pipe axis.

The length of pipe that can be constructed in such a way is dictated bythe length of the mandrel or the roll of pipe that can be transported.Consequently, the construction process is not conducive to constructionof long pipes to form a transportation network for liquids and gasses;that is, pipes which are much longer than available mandrels and alsopipes which are of a length to constitute a pipeline extendingcontinuously between two distant locations, perhaps hundreds tothousands of kilometres apart.

It would be advantageous for there to be a way in which a pipeline couldbe constructed using a pipe constructed on a continuous basis; that is,without having to be composed of a series of relatively short pipesections joined one to another at junctions which are likely constitutedareas of weakness in structural integrity of the pipeline There may,however, be circumstances where the pipeline cannot be constructed usinga single pipe constructed on a continuous basis. In such circumstances,the pipeline may be constructed using a plurality of pipes eachconstructed on a continuous basis and connected one to another. Thismay, for example, apply to a pipeline which is required to beconstructed in more than one pipe production run, in which case acontinuous pipe produced in one production run would need to beconnected to a pipe produced in a successive production run.

Construction of pipeline on a continuous basis is proposed in theApplicant's international application PCT/AU2011/001401, the contents ofwhich are incorporated herein by way of reference.

The pipeline is of composite construction, comprising a radially innerportion and a radially outer portion, with the two portions mergingtogether to provide an integrated tubular wall structure. The innerportion is configured as an inner tube constructed from an inner linerwith a layer of resin absorbent material bonded onto one face thereof.The other face of the inner liner defines the interior surface of thepipe. Typically, the liner presents a high gloss surface at the innerface. The inner liner may, for example, comprise polyurethane,polyethylene or any other resiliently flexible material which ispreferably also impervious to air and also compatible to fluid to beconveyed within the pipe. The resin absorbent layer may, for example,comprise felt or flock.

The inner tube is constructed from a strip of material which providesthe inner liner by rolling the strip longitudinally into a tubularconfiguration.

The outer portion is configured as an outer tube of fibre reinforcedcomposite construction surrounded by a flexible outer casing. Moreparticularly, the outer tube comprises reinforcement impregnated in aresinous binder. The flexible outer casing is installed around the outertube to contain the resinous binder, and may remain in place andultimately form an integral part of the pipe or it may be subsequentlyremoved after having served its purpose.

The resinous material which provides the resinous binder may be of anyappropriate type; a particularly suitable resinous material may comprisethermosetting resin such as epoxy vinyl ester or other suitable resinand thermoplastic resin systems.

The reinforcement may comprise one or more layers of reinforcing fabric,each layer being configured as a tubular layer disposed about the innertube. The reinforcing fabric may comprise reinforcing fabric whichincorporates reinforcement fibres featuring quad-axial fibreorientations. The reinforcement fibres may comprise glass fibres. Thequad-axial fibre orientations offer the necessary hoop and axial stressbearing properties to the pipe.

Constructing the inner tube from a strip of material which is rolledlongitudinally into a tubular configuration is not particularlyconducive to cost-effective manufacture on a large scale. Further,constructing the outer tube as one or more layers of reinforcing fabricin a tubular arrangement about the inner tube can present challenges.Accordingly, it may be advantageous to pre-fabricate the assembly of theinner portion and the outer portion, and deliver the prefabricatedassembly to the site at which the pipeline is to be constructed andlaid. Further, it may be advantageous to install the flexible outercasing about the assembly of the inner portion and the outer portion,and also introduce the resinous binder to impregnate the reinforcement,at the site during construction of the pipeline.

It is against this background, and the problems and difficultiesassociated therewith, that the present invention has been developed.

More particularly, an aspect of the present invention seeks to installthe flexible outer casing about the prefabricated assembly of the innerportion and the outer portion and also introduce the resinous binder toimpregnate the reinforcement.

SUMMARY OF INVENTION

According to a first aspect of the present invention there is provided amethod of constructing a tubular assembly comprising an inner portionand a further portion surrounding the inner portion, the methodcomprising: provided a prefabricated tubular assembly to provide theinner portion; the prefabricated tubular assembly comprisingreinforcement; providing a strip of material to form the furtherportion, causing the strip to wrap about and surround the prefabricatedtubular assembly; and introducing resinous binder into the reinforcementas the strip is being wrapped about the prefabricated tubular assembly.

The resinous binder may be introduced into the reinforcement through asurface over which the prefabricated tubular assembly is caused to move.

The surface may have a least one port through which the resinous binderis delivered to the reinforcement

The resinous binder may be introduced into the reinforcement byinjection.

The further portion may provide an outer casing about the inner portion.

The outer casing may comprise a flexible outer casing.

The flexible outer casing may have some resilience in order to yieldingresist radial expansion of the reinforcement. In this way, the flexibleouter casing may function to control the rate of radial expansion of thereinforcement.

The reinforcement may comprise a plurality of layers configured astubular layers disposed one about another.

Each tubular layer may comprise a strip having a central longitudinalportion and two longitudinal marginal side portions on opposed sides ofthe central longitudinal portion, the strip being assembled into atubular configuration with the two marginal side portions being disposedin overlapping relation and affixed together to provide a longitudinallap seam, the longitudinal lap seam being constructed to facilityslippage between the two marginal side portions.

With this arrangement, the two marginal side portions of each layer areyieldingly connected together at the longitudinal lap seam.

The slippage may be a controlled slippage in the sense that it occurs inselected circumstances, such as radial expansion of the respectivetubular layer.

The slippage may be controlled (predetermined or designed) to ensurethat loading generated by expansion of the inner tube upon inflationthereof is able to be transferred successively through the surroundinglayers outwardly from the innermost layer.

The slippage may comprise some relative movement between the twomarginal side portions within the longitudinal lap seam.

The flexible outer casing may function to control the rate of radialexpansion of the reinforcement.

The inner portion may further comprise an inner tube about which thereinforcement is disposed.

The method may further comprise radially expanding the inner tube,wherein the radially expanding inner tube may operate in conjunctionwith the flexible outer casing to confine the reinforcement and alsocauses a space between the inner tube and the outer casing within whichthe reinforcement is confined to progressively decrease. This may forcethe resinous binder introduced into the reinforcement to fullyimpregnate the reinforcement.

Expansion of the inner tube causing loading to be transferredsuccessively through the surrounding layers outwardly from the innermostlayer, progressively tensioning the reinforcement.

The resinous binder is caused to move through the reinforcement withinthe space as a progressively rising resin pool as a consequence of theprogressively decreasing volume of the space. The resinous binder mayalso function as a lubricant to facilitate slip between adjacent layersupon continued radial expansion of the inner tube

Inflation of the inner tube brings the inner tube into direct contactwith the reinforcement, and also brings the reinforcement into directcontact with the outer casing (through the resinous binder if present).

Progressive decrease in volume of the space in which the reinforcementis confined, acts to positively expel air from within the space whichhas the effect of enhancing impregnation of the resinous binder withinthe reinforcement. The outer casing and the various tubular layersconstituting the reinforcement may be adapted to facilitate theexpulsion of the air. By way of example, interstices within the tubularlayers which constitute the reinforcement may provide pathways for airexpulsion. Further, the outer casing and possibly also the tubularlayers may incorporate vents at intervals along their respective lengthsto facilitate introduction of the resinous binder and expulsion of theair.

The outer casing is adapted to sustain the inflation pressure andconstrain expansion of the reinforcement. The outer casing yieldingresists expansion of the reinforcement and is so doing serves to controlthe expansion of the reinforcement. In particular, the outer casing hasthe effect of limiting the extent of slippage within the longitudinalseams of the tubular layers, thereby limiting the expansion of thereinforcement. In other words, the outer casing prevents over expansionof the reinforcement.

According to a second aspect of the invention there is providedapparatus for performing the method according to the first aspect of theinvention.

According to a third aspect of the invention there is provided apparatusfor constructing a tubular assembly comprising an inner portion and afurther portion surrounding the inner portion, the inner portioncomprising reinforcement and the further portion being formed from astrip of material comprising two opposed longitudinal marginal sideportions; the apparatus comprising: an assembly station comprising awall; means for advancing the inner portion along a first path extendingpassed the wall; means for advancing the strip along a second path andcausing the strip to encircle the wall and thereby wrap about andsurround the inner portion, and means for introducing resinous binderinto the reinforcement as the strip is being wrapped about theprefabricated tubular assembly.

The apparatus may comprise a surface over which the inner portion iscaused to move.

The means for introducing resinous binder into the reinforcement maycomprise the surface, wherein resinous binder can be delivered into thereinforcement through the surface.

The surface may have a least one port through which the resinous binderis delivered to the reinforcement.

The term “concentrically”, and related term “concentric”, as used hereinrefers to an arrangement comprising a plurality of layers one encirclinganother. The layers may simply be wrapped one about another, and neednot necessarily have a common geometric centre.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the present invention are more fully described inthe following description of several non-limiting embodiments thereof.This description is included solely for the purposes of exemplifying thepresent invention. It should not be understood as a restriction on thebroad summary, disclosure or description of the invention as set outabove. The description will be made with reference to the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view of a pipe comprising a radially innerportion and a radially outer portion, with the two portions mergingtogether to provide an integrated tubular wall structure;

FIG. 2 is a view of a prefabricated tubular assembly providing the innerportion and outer portion for use in construction of the pipe shown inFIG. 1, the prefabricated tubular assembly being shown in a “lay-flat”condition;

FIG. 3 is a view similar to FIG. 2, except that the prefabricatedtubular assembly is shown in an expanded condition;

FIG. 4 is a further view of the prefabricated tubular assembly shown ina “lay-flat” condition but opened somewhat to reveal internal parts;

FIG. 5 is a schematic perspective view of a layer of the prefabricatedtubular assembly undergoing a garniture wrapping process;

FIG. 6 is a schematic perspective view of the layer of FIG. 5 beingwrapped about an inner tube to provide an innermost layer;

FIG. 7 is a view similar to FIG. 6 but showing a further layer beingwrapped about the inner tube and the previous layer;

FIG. 8 is a view similar to FIG. 7 but showing a further layer beingwrapped about the inner tube and the previous layer;

FIG. 9 is a view similar to FIG. 8 but showing an infusion media layerbeing wrapped about the inner tube and the previous layer;

FIG. 10 is a fragmentary side view of the tubular innermost layer,illustrating in particular two marginal side portions disposed inoverlapping relation and affixed together to provide a longitudinal lapseam;

FIG. 11 is a fragmentary perspective view of the two marginal sideportions disposed in overlapping relation and affixed together toprovide the longitudinal lap seam;

FIG. 12 is a schematic cross-sectional view of the innermost layer,illustrating in particular the extent of overlap between the twomarginal side portions prior to slippage with the longitudinal lap seam;

FIG. 13 is a is a view similar to FIG. 12 but showing the extent ofoverlap between the two marginal side portions after to slippage withthe longitudinal lap seam;

FIG. 14 is a schematic view depicting various operations performed toinstall the innermost layer about the inner tube;

FIG. 15 is a schematic perspective view of part of assembly apparatusprovided for production of the prefabricated tubular assembly;

FIG. 16 is an end view of part of assembly apparatus provided forproduction of the prefabricated tubular assembly;

FIG. 17 is a plan view of the arrangement shown in FIG. 16;

FIG. 18 is a further schematic perspective view of part of assemblyapparatus provided for production of the prefabricated tubular assembly,illustrating in particular an alignment device comprising a guidemounted on a plate structure;

FIG. 19 is an end view of the arrangement shown in FIG. 18;

FIG. 20 is an end view of the guide on an enlarged scale;

FIG. 21 a further schematic perspective view of part of assemblyapparatus provided for production of the prefabricated tubular assembly,illustrating in particular a guidance system for guiding the strip tomaintain the two longitudinal marginal side portions in correctalignment with the guide;

FIG. 22 is a schematic view illustrating operation of the guidancesystem in one condition;

FIG. 23 is a schematic view illustrating operation of the guidancesystem in another condition;

FIG. 24 is a schematic view illustrating operation of the guidancesystem in another condition;

FIG. 25 a schematic view illustrating a variation of the guidancesystem;

FIG. 26 depicts a mobile facility for production of the pipe, the mobilefacility including an assembly apparatus to install a flexible outercasing around the prefabricated tubular assembly to provide theassembled tubular structure;

FIG. 27 depicts, schematically, inflation of an assembled tubularstructure as part of the production process;

FIG. 28 depicts, schematically, inflation of the assembled tubularstructure and movement of resinous binder through reinforcement withinthe assembled tubular structure;

FIG. 29 is a schematic view depicting various operations performed toinstall a flexible outer casing around the prefabricated tubularassembly to provide the assembled tubular structure;

FIG. 30 a schematic perspective view of part of the assembly apparatus,illustrating in particular a guidance system for guiding the strip tomaintain the two longitudinal marginal side portions in correctalignment with the guide;

FIG. 31 a further schematic perspective view of part of the assemblyapparatus;

FIG. 32 a further schematic perspective view of part of the assemblyapparatus; and

FIG. 33 a schematic view illustrating a variation of the guidancesystem;

In the drawings like structures are referred to by like numeralsthroughout the several views. The drawings shown are not necessarily toscale, with emphasis instead generally being placed upon illustratingthe principles of the present invention.

The figures depict several embodiments of the invention. The embodimentsillustrate certain configurations; however, it is to be appreciated thatthe invention can take the form of many configurations, as would beobvious to a person skilled in the art, whilst still embodying thepresent invention. These configurations are to be considered within thescope of this invention.

DESCRIPTION OF EMBODIMENTS

This disclosure is concerned with construction of a pipeline 10 ofcomposite construction. The pipeline 10 comprises pipe 20 comprising aradially inner portion 21 and a radially outer portion 22, with the twoportions 21, 22 merging together about an outer casing 23 to provide anintegrated tubular wall structure 25.

The integrated tubular wall structure 25 may be encased within aprotective sheath comprising a hardenable composition such as cement orconcrete contained by an outermost skin of any suitable material, suchas geotextile cloth. Such a protective sheath is intended to affordprotection to the pipe 20 against compression loading to which it mightbe exposed once in the installed condition. However, it likely that theprotective sheath will not be employed in many instances; for example,in underground applications. In other applications, such as for exampleexposed application (above ground for instance) and in marineapplications, the protective sheath may provide a surface exposed to thesurrounding environment.

The inner and outer portions 21, 22 are integrated into a prefabricatedtubular assembly 24, as will be described in more detail later. Theprefabricated tubular assembly 24 is of a multi-layer construction. Theprefabricated tubular assembly 24 would typically be produced at aproduction facility and transported to site for use in construction ofthe pipe 20. The prefabricated tubular assembly 24 would typically beadapted to assume a compact condition for storage and transportation.For example, the prefabricated assembly 24 may be adapted to assume alay-flat state and then be stored in a manner facilitating deployment asrequired; for example, it may be stored in a folded condition withsections thereof folded back-and-forth one upon another or stored in arolled condition upon a reel. The prefabricated assembly 24 wouldtypically be provided in lengths, each length being adapted to assumethe lay-flat state and stored as described.

The inner portion 21 comprises an inner tube 30. Prior to formation ofthe integrated tubular wall structure 25 of the pipe 20, the inner tube30 defines an inflatable bladder 31 having an inflation cavity 33. Withthis arrangement, the inner tube 30 can be caused to undergo radialexpansion upon inflation of bladder 31 by introduction of an inflationfluid such as, for example, air or water. The inflation pressurerequired to inflate the inner tube 30 and support reinforcement withinthe outer portion 22 after wet-out but before gelation and curing (whichreinforcement will be described later) is relatively low; typically inthe order of 5-30 psi or 0.3-2 bar.

Upon formation of the integrated tubular wall structure 25, the innertube 30 also defines the interior wall 34 of the pipe 20.

The outer portion 22 is of annular formation, being configured as anouter tube 35 comprising reinforcement 37 for impregnation by a resinousbinder. The flexible outer casing 23 is disposed around the outer tube35 to contain resinous binder impregnating the reinforcement 37 prior tocuring to provide the outer tube 35.

The flexible outer casing 23 may have some resilience in order toyielding resist radial expansion of the reinforcement. In this way, theflexible outer casing may function to control the rate of radialexpansion of the reinforcement.

The flexible outer casing 23 may be formed of any appropriate material,including for example polyethylene. The outer casing 23 may remain inplace and ultimately form an integral part of the pipe 20, or it may besubsequently removed after having served its purpose in the constructionprocess.

The outer casing 23 may comprise an outer layer of polyethylene or TPUor PVC, and a fibrous layer bonded onto one face thereof, thearrangement being that the fibrous layer confronts the reinforcement 37.The fibrous layer provides reinforcement of the outer casing 23 so thatit provides the restraining force for the controlled expansion of theprefabricated tubular assembly 24. The fibrous layer may provide abreather layer and may also be ultimately impregnated with the resinousbinder for integration of the prefabricated tubular assembly 24.

The prefabricated tubular assembly 24 and the surrounding outer casing23 together provide an assembled tubular structure 40 which isultimately formed into pipe 20.

The resinous material which provides the resinous binder may be of anyappropriate type. A particularly suitable resinous material may comprisethermosetting resin such as epoxy vinyl ester or other suitable resinand thermoplastic resin systems.

The reinforcement 37 may comprise one or more layers 41 of reinforcingmaterial, each layer 41 being configured as a tubular layer disposedsomewhat concentrically about the tube 30. The reinforcing material maycomprise fabric; preferably, woven reinforcing fabric or non crimpedfabric such as SAERTEX stitched quad-axial, which incorporatesreinforcement fibres featuring quad-axial fibre orientations. Thequad-axial fibre orientations offer the necessary hoop and axial stressbearing properties to the pipe. The reinforcement fibres may compriseglass fibres, although other reinforcement fibres are also contemplated

The various concentric reinforcing fabric tubular layers 41 are sizedone with respect to another to facilitate slip between the layers uponradial expansion of the inner tube 30 about which they are disposed. Asthe layers 41 expand, the reinforcement fibres featuring quad-axialfibre orientations progressively tension.

The prefabricated tubular assembly 24 may further comprise infusionmedia to facilitate distribution of the resinous binder required toimpregnate the layers 41 of reinforcing fabric. The infusion media maybe provided as a tubular layer 43 concentrically surrounding the layers41 of reinforcing fabric. With this arrangement, the infusion medialayer 43 may function as an outer skin for the prefabricated tubularassembly 24.

The flexible outer casing 23 serves to resist radial expansion of theconcentric reinforcing fabric tubular layers 41 (which constitute thereinforcement 37) upon radial expansion of the inner tube 30, therebycausing the reinforcement 37 to be subjected to radial compression. Withthis arrangement, the reinforcement 37 is confined in a space 42 betweenthe expanding inner tube 30 and the flexible outer casing 23.Specifically, the radially expanding inner tube 30 operates inconjunction with the flexible outer casing 23 to confine thereinforcement 37 and also causes the volume of the space 42 in which thereinforcement is confined to progressively decrease. This forces theresinous binder within the reinforcement 37 to fully impregnate thereinforcement; that is, the layers 41 of reinforcing fabric (configuredas the tubular layers which constitute the reinforcement) become fully“wetted-out”. In particular, it provides a compaction force to thereinforcement 37 and effectively pumps the resinous binder through thelayers of reinforcing fabric to distribute the resinous binder withinthe space in a controlled and constrained manner. The resinous binder iscaused to move through the reinforcement 37 within the space as aprogressively rising resin pool as a consequence of the progressivelydecreasing volume of the space. The progressively rising resin pool isakin to a wave of resin The resinous binder may also function as alubricant to facilitate slip between adjacent layers 41 upon continuedradial expansion of the inner tube 30

It is a particular feature of this process that the step of deliveringresinous binder to the reinforcement 37 (being the concentric layers41), and the step of fully wetting out the reinforcement with theresinous binder, are separate and distinct actions, as will be explainedfurther later.

Further, the progressive decrease in volume of the space 42 in which thereinforcement 37 is confined, acts to positively expel air from withinthe space which has the effect of enhancing impregnation of the resinousbinder within the reinforcement. The outer casing 23 and the variousreinforcing fabric tubular layers 41 (which constitute the reinforcement37) may be adapted to facilitate the expulsion of the air. By way ofexample, any breather layer defined by the fibrous inner layer of theouter casing 23 may facilitate this expulsion of air. Further,interstices within the reinforcing fabric tubular layers whichconstitute the reinforcement may provide pathways for air expulsion.Still further, the outer casing 23 and possibly also some of the variousreinforcing fabric tubular layers may, for example, incorporate vents atintervals along their respective lengths to facilitate expulsion of theair. In one arrangement, the vents may comprise perforations, such aspuncture holes, formed in the outer casing 23. With such an arrangement,the perforations are ultimately sealed by the resinous binder to ensurethe sealed integrity of the pipe 20. In another arrangement, the ventsmay comprise ports inserted in the outer casing 23 and the variousreinforcing fabric tubular layers which constitute the reinforcement 37.The ports may, for example, comprise tubular inserts formed of amaterial which dissolves or otherwise degrades upon exposure to theresinous binder. With such an arrangement, the apertures in which theports were accommodated are ultimately sealed by the resinous binder toensure the sealed integrity of the pipe 20.

The flexible outer casing 23 may have some resilience in order toyielding resist radial expansion of the concentric reinforcing fabrictubular layers 41 (which constitute the reinforcement 37), at least tosome extent. In this way, the flexible outer casing 23 can cushion theinitial stage of the radial expansion of the reinforcing fabric tubularlayers. In particular, it is desirable that the flexible outer casing 23have some elasticity; for example, elasticity in the range of about 1%to 10%. The flexible outer casing 23 may have some elasticity for thepurpose of enhancing control of the rate at which the progressivelyrising pool of resinous binder progressively wets the reinforcement 37.Control of the rate at which the progressively rising pool of resinousbinder progressively wets the reinforcement 37 is desirable. If, forexample, the resinous binder rises within the space too rapidly, it maybe that full wet-out of fibres in the reinforcement 37 might not beachieved, with the result only a layer of resin encases the fibrebundles but does not fully wet the fibres at the centre of the fibrebundle. If, on the other hand, the resinous binder rises within thespace too slowly, it may be that the resinous binder could commence tocure before full wet-out of fibres in the reinforcement 37 is achieved.

The elastic nature of the flexible outer casing 23 installed around thereinforcement 37 functions somewhat as a girdle for controlling externalpressure exerted on the rising pool of resinous binder. The elasticcharacteristic of the flexible outer casing 23 is selected to achievethe desired rate of wet-out. The elastic force exerted by the outercasing 23 provides some counterbalancing of the tension exerted by theinflating bladder 31 defined by the inner tube 30. Inflation of theassembled tubular structure 40 brings the inner tube 30 into directcontact with the reinforcement 37, and also brings the reinforcement 37into direct contact with the outer casing 23.

The inflatable bladder 31 is typically maintained in the inflatedcondition until such time as the resinous binder has hardenedsufficiently to maintain the form and shape of the pipe 20, after whichthe inflation fluid can be released from the inflation cavity 33. Thepipe 20 is thus formed, with the inner tube 30 defining the central flowpassage within the pipe.

In order to inflate the inner tube 30 and the assembled tubularstructure 40, it is necessary to close the inner tube 30. This is doneby locally compressing the assembled tubular structure 40 to establish aclosure zone at a location distal to an end from which the inflationfluid is introduced so that inflation fluid cannot pass through, andprogressively moving the local compression along the tubular structureto progressively advance the closure zone along the inner.

The prefabricated tubular assembly 24 is produced at a productionfacility featuring an assembly station(s) 100 at which the variouslayers 41, 43 are installed about the inner tube 30. The prefabricatedtubular assembly 24 would be transported from the production facility tosite for use in construction of the pipe 20.

The inner portion 21 comprises tube 30, and the outer portion 22comprises one or more layers 41 of reinforcing fabric and optionallyalso infusion media layer 43. Each layer 41, 43 is configured as atubular layer disposed concentrically about the tube 30. The infusionmedia layer 43 (when used) is disposed about the layers 41 ofreinforcing fabric. The various layers 41, 43 are limp, as best seen inFIG. 4, as they are typically formed from pliant woven reinforcingfabric. However, for clarity, the various layers 41, 43 are depicted invarious other figures of the drawings as if they featured straightsections, betraying their limp nature.

Each layer 41, 43 is formed from a strip 50 in the form of a web orribbon. The strip 50 comprises a central longitudinal portion 51 and twolongitudinal marginal side portions 53 on opposed sides of the centrallongitudinal portion. The strip 50 is typically of unitary construction,with the central longitudinal portion and two longitudinal marginal sideportions being zones of the unitary strip identified for referencepurposes, rather than being distinct or separate parts. However, thestrip 50 need not necessarily be of unitary constriction, and thecentral longitudinal portion 51 and two longitudinal marginal sideportions 53 may alternatively comprise distinct or separate parts joinedtogether. By way of example, in certain circumstances each layer maycomprise sections of laminates jointed together to provide the requiredwidth of strip. This may be necessary for large diameter pipes, forinstance, as the width of strip required may not be able to be producedby conventional stitching machines used to produce fabric laminates.Further, joining sections of laminates together to provide the requiredwidth of strip allows remnant material to be used to provide the strip.

The strips 50 are each successively garniture wrapped around the innertube 30 (and any preceding layer 41 about the inner tube 30) to assemblethe strip into a tubular configuration providing the respective tubularlayer 41. FIG. 5 depicted strip 50 being progressively folded uponitself from a flat configuration at section 50 a into a tubularconfiguration at section 50 b. In the tubular configuration into whichsection 50 b is folded, the two marginal side portions 53 are disposedin overlapping relation and affixed together to provide a longitudinallap seam 55.

In being garniture wrapped around the inner tube 30, each strip 50 isprogressively folded upon itself along its length, maintaining thedirection of the laminate in alignment with the axis of the pipeultimately produced, with the two marginal side portions 53 beingbrought together into overlapping relation, as illustrated schematicallyin FIGS. 6 to 8. With this arrangement, each successive layer 41 iswrapped about the previous layer to provide the prefabricated tubularassembly 24; that is, the first layer 41 a is wrapped about the tube 30,the next layer 41 b is wrapped about preceding layer 41 a, and eachsucceeding layer is wrapped about the preceding layer. FIG. 12 similarlyshows the infusion media layer 43.

The wrapping process whereby each strip 50 is progressively folded uponitself along its length, with the two marginal side portions 53 beingbrought together into overlapping relation is somewhat similar to agarniture wrapping process used in the production of cigarettes.

The two marginal side portions 53 of each respective strip 50 areaffixed together in any appropriate manner to provide the longitudinallap seam 55.

The two marginal side portions 53 of each respective strip 50, or atleast some of the strips, are not affixed together permanently. Rather,the marginal side portions 53 are affixed together temporarily. This isto provide for some slippage between the two marginal side portions 53within the longitudinal lap seam 55. With this arrangement, the twomarginal side portions 53 are yieldingly connected together at thelongitudinal lap seam 55.

Specifically, the marginal side portions 53 may be capable of slippinglaterally (tangentially) with respect to each other, after assembly ofthe prefabricated tubular assembly 24; for example, during deployment ofthe prefabricated tubular assembly 24, and more particularly duringradial expansion of the concentric reinforcing fabric tubular layers 41(which constitute the reinforcement 37) upon inflation of the tube 30.The slippage may comprise some relative movement between the twomarginal side portions 53 within the longitudinal lap seam 55 or the twomarginal side portions 53 detaching from each other to rupture thelongitudinal lap seam 55. With such slippage, each tubular layer 41 canexpand radially beyond the extent to which it could otherwise expand byvirtue of inherent expansion available in the fabric from which thelayer is formed. The additional radial expansion arising from slippagebetween the marginal side portions 53 comprising the longitudinal lapseam 55 of each layer, permits loading to be transferred successivelythrough the layers 41 outwardly from the innermost layer 41 a duringexpansion of the tube 30 upon inflation thereof. As the layers 41expand, the reinforcement fibres featuring quad-axial fibre orientationsprogressively tension (as stated above).

The slippage may be a controlled slippage in the sense that it occurs inselected circumstances, such as radial expansion of the respectivetubular layer 41.

The slippage may controlled (predetermined or designed) to ensure thatloading generated by expansion of the inner tube 30 upon inflationthereof is able to be transferred successively through the surroundinglayers 41 outwardly from the innermost layer 41 a.

The slippage may comprise some relative movement between the twomarginal side portions 53 within the longitudinal lap seam 55.

The flexible outer casing 23 may function to control the rate of radialexpansion of the reinforcement.

By way of example only, the tubular layers 41 might possibly expand some3% to 15% of their initial diameter upon inflation of the inner tube 31within the prefabricated tubular assembly 24. Of this expansion, some 1%to 5% may be attributable to inherent expansion available within thefabric material(s) from which the layers 41 are made, with the balancebeing attributable to slippage between the marginal side portions 53comprising the longitudinal lap seam 55 of each layer.

The extent of overlap between the two overlapping marginal side portions53 within the longitudinal lap seam 55. may be of any appropriateamount, but is typically about 35 to 125 mm or 1% to 10% of the totalwidth of the strip 50. Preferably, the extent of overlap should not beso much as to create a capstan effect which might impede slippage withinthe longitudinal lap seam 55.

In this embodiment, the two marginal side portions 53 of each strip 50are adhered together, such as by way of adhesive bonding. The adhesivebond may be provided by an adhesive substance, such as hot meltadhesive. The adhesive bond is best seen in FIGS. 10 and 13, and isidentified by reference numeral 57. While the adhesive bond 57 mayoptionally be continuous along the length of the longitudinal lap seam55, it is preferably discontinuous, providing bonding attachment atspaced intervals; that is, the adhesive bond 57 preferably comprisesbond sections 57 a spaced at intervals along the longitudinal lap seam55, as shown in FIG. 13. The adhesive bond 57 may comprise one or morelines of adhesive. Where there are two or more lines of adhesive, eachmay be discontinuous, with the discontinuities between adjacent lines ofadhesive being staggered.

The adhesive bond 57 is adapted to rupture, or at least partiallyrelease, after bonding to facilitate slippage between the two marginalside portions 53, upon inflation of the tube 30. The slippage may beaccommodated by flexibility within the adhesive bond 57.

The nature of the adhesive bond 57 can vary according to characteristicsof the fibre materials from which the layers 41 are made. Thesecharacteristics may, for example, include: the varieties of fibre blendswithin the woven fabric material; the size of the fibres; the angles ofthe fibre rovings; the surface finish of the fibre bundles; variationsin machine stitching during manufacture of the woven fabric material;and water content.

The nature of the adhesive bond 57 is preferably selected to establish alight-touch contact bond between the two marginal side portions 53between which the bond is to be established. Desirably, the contact bondshould be just sufficient to satisfy bonding requirements, withoutadversely wetting the fibre bundles within the two confronting marginalside portions 53. It is desirable to avoid wetting the fibre bundleswith the adhesive substance, as it can be detrimental to subsequentimpregnation of resin binder at the location of the bond.

The adhesive substance providing the adhesive bond 57 may comprise apolyamide, such as molten Kevlar, applied at a temperature of about 225°C. However, a variety of other types of adhesive substance may be used,as would be understood by a person skilled in the art.

The slippage within one longitudinal lap seam 55 is depictedschematically in FIGS. 12 and 13. FIG. 12 shows the longitudinal lapseam 55 in a condition prior to slippage; that is, when the longitudinallap seam 55 is first formed by affixing the overlapping marginal edgeportions 53 of the strip 50 together. The extent of overlap isidentified by reference character A. FIG. 13 shows the longitudinal lapseam 55 in a condition following slippage, with a reduced amount ofoverlap between the marginal edge portions 53. The extent of overlapafter slippage is identified by reference character B. The extent ofoverlap between the two overlapping marginal side portions 53 afterslippage may be of any appropriate amount, but is typically at least 10times the thickness of the strip (laminate) from which the layer isformed. This is to ensure that there is sufficient overlap for transferof the shear loads; for example, if the strip (laminate) is 1.8 mmthick, an overlap of 18 mm should be maintained at the longitudinal lapseam 55 of each layer to effectively transfer the shear loads.

By way of example only, the amount of overlap may be about 30 to 125 mmwhen the longitudinal lap seam 55 is first formed, and about 15 to 35 mmfollowing slippage within the longitudinal lap seam.

The integrity of the radially outer portion 22 of the composite pipe 20ultimately formed using the prefabricated tubular assembly 24 is notcompromised by slippage within the longitudinal lap seam 55 of eachlayer 41, or rupturing or partial release, of the adhesive bond 57within the longitudinal lap seam 55. This is because the layers 41 areultimately impregnated with resin binder which cures, encasing thelayers. The longitudinal lap seams 55 are intended to maintain thevarious layers 41 in the tubular arrangement concentrically one aboutanother during manufacture and during deployment of the prefabricatedtubular assembly 24. Subsequent slippage within the longitudinal lapseams 55 enables the tubular layers 41 to expand radially beyond theextent to which they could each otherwise do so. In this way, loadinggenerated by expansion of the tube 30 upon inflation thereof can betransferred successively through the surrounding layers 41 outwardlyfrom the innermost layer 41 a, progressively tensioning thereinforcement fibres within the material from which the layers 41 areformed (e.g the quad-axial fibre orientations).

The longitudinal lap seams 55 of adjacent layers 41 are angularly offsetin relation to each other. This can be seen in FIGS. 3 and 9, with thelatter showing the longitudinal lap seams 55 of adjacent layers 41 a, 41b and 41 c are in angularly spaced relation. This is to distribute thelongitudinal lap seams 55 around the reinforcement 37 and avoid bulgesor excess thickening of the prefabricated tubular assembly 24

Referring now to FIGS. 14 to 25, there is shown one form of assemblyapparatus 100 for production of the prefabricated tubular assembly 24.

The prefabricated tubular assembly 24 is produced by firstly wrapping afirst layer 41 a (which constitutes the innermost layer) about the tube30. A second layer 41 b is then wrapped about the innermost layer 41 a.This is followed by wrapping of a third layer 41 c about the secondlayer 41 b. The process is repeated until all required layers 41 are inposition. Additionally, if infusion media is to be provided, theinfusion media layer 43 is wrapped about previously installed concentriclayers 41. FIG. 14 only depicts wrapping of the innermost layer 41 aabout the inner tube 30.

This production of the prefabricated tubular assembly 24 may involvevarious passes of the tubular assembly 24 under construction through theapparatus 100, with each pass installing the next layer. Alternatively,the apparatus 100 may have a plurality of stations in series, with eachstation installing a respective one of the various layers configuredabout the circumference such that the overlaps which provide thelongitudinal lap seams are evenly distributed about the circumference.

The assembly apparatus 100 will now be described with reference toinstallation of the innermost layer 41 a about the tube 30. However, itshould be understood that a similar procedure is involved ininstallation of any subsequent layer (either layer 41 of reinforcingfabric, or the infusion media layer 43) about that portion of tubularassembly 24 which has been previously assembled through installation ofone or more preceding layers.

The tube 30 is prefabricated prior to being used in the production ofthe assembled tubular structure 40.

The various operations performed by the assembly apparatus 100 toinstall the innermost layer 41 a about the inner tube 30 are depictedschematically in FIG. 14, featuring a folding station 101, a steeringstation 102, a monitoring station 103, an overlapping station 104, abonding station 105, and an assembly station 106. The assembly station106 is integrated with the overlapping station 104 and the bondingstation 105.

Operations at the steering station 102 and a monitoring station 103 maybe under the control of a control system 107 such as a computer controlsystem. The control system 107 may also control other aspects of theassembly apparatus 100.

The inner tube 30 advances along a first path 111 towards the assemblystation 106.

The layer 41 a is formed from strip 50 in the form of a web 115advancing along a second path 112 towards the folding station 101. Theweb 115 may be stored on a reel (not shown) from which it canprogressively unwind and advance towards the folding station 101.

In advancing along the second path 112, the web 115 providing the strip50 is progressively folded from a flat condition into a tubularconfiguration with the two longitudinal marginal side portions 53 inoverlapping relation, as illustrated in FIG. 8 discussed previously.Various guide elements are provided along the path 112 of movement ofthe web 115 for progressively causing the strip 50 to assume the tubularconfiguration at section 50 b with the two longitudinal marginal sideportions 53 in overlapping relation. The guide elements may include turnelements about which the web 115 is turned for directional control, anda profiling structure for causing the web 115 to fold longitudinally toprogressing urge the central portion 51 to assume an arcuate profile andmove the two longitudinal marginal side portions 53 inwardly towardseach other. The folding station 101 comprises two sections 101 a and 101b, each associated with one of the two longitudinal marginal sideportions 53 of the strip 50.

The assembly apparatus 100 comprises a plate structure 121 defining awall 122, as shown in FIG. 15. In the arrangement shown, the first path111 passes below the wall 122 and the second path 112 surrounds the wall122.

The assembly apparatus 100 further comprises a base portion (not shown)mounted below the plate structure 121.

The base portion and the plate structure 121 cooperate to define a space125 through which the first path 111 extends. With this arrangement, thetube 30 passes through the space 125, as depicted schematically in FIG.15 which also shows the tube 30 exiting the space.

As the tube 30 passes through the space 125, the strip 50 is wrappedaround the tube 30 to form the innermost layer 41 a, as shownschematically in FIG. 19.

More particularly, the strip 50 progressively assumes the tubularconfiguration as it approaches the assembly station 106. Upon arrival ofthe strip 50 at the assembly station 106, the tubular configurationencircles the base and the plate structure 121, and thus also the tube30 passing through the space 125, as best seen in FIGS. 15 and 16. Withthis arrangement, the innermost layer 41 a is installed completely aboutthe tube 30 upon the assembly exiting from the space 125.

The bonding station 105 comprises a system 131 for affixing the twolongitudinal marginal side portions 53 together in overlapping relationto complete assembly the strip 50 into a tubular configuration toprovide the innermost layer 41 a about the tube 30.

The system 131 for affixing the two longitudinal marginal side portions53 together in overlapping relation may take any appropriate form. Inthe arrangement shown, the system 131 comprises apparatus 133 forapplying hot melt adhesive between the overlapping longitudinal marginalside portions 53 to establish adhesive bonding therebetween (e.g. theadhesive bond 57). The apparatus 133 may comprise an delivery device forspraying or otherwise propelling adhesive between the overlappinglongitudinal marginal side portions 53 to effect adhesive bonding.

The wall 122 at the assembly station 106 presents a wall surface 141along which the two longitudinal marginal side portions 53 slide, and apress (not shown) may optionally be provided for pressing the twolongitudinal marginal side portions 53 together against the wall surfaceto establish adhesive bonding therebetween. Consistent with therequirement for a light-touch contact bond between the two marginal sideportions 53 between which the bond is to be established, the press maybe configured for lightly pressing the two portions 53 together. Thepress may comprise a press roller system, with the overlapping marginalside portions 53 passing between the press roller system and the wallsurface. The press may also incorporate a cooling means for chilling theadhesive and or the roller to bring the adhesives temperature down belowthe molten state to achieve the bond quickly.

The apparatus 133 for applying hot melt adhesive between the overlappinglongitudinal marginal side portions 53 may be mounted on a lateral railsystem (not shown), permitting selective positional adjustment, as maybe required.

The assembly apparatus further comprises an alignment system 151 foraligning the two longitudinal marginal side portions 53 in overlappingrelation prior to being affixed together. The alignment system 151comprises an alignment device 161. The alignment device 161 is providedat or adjacent the overlapping station 104.

The alignment device 161 comprise a guide 163 mounted on the platestructure 121, as shown in FIGS. 16 to 20. In FIG. 20, the guide 163 isdepicted schematically in an enlarged condition.

In the arrangement shown, the guide 163 comprises two guide platesfitted together. The guide 163 defines two longitudinal guide paths 165,167, each having an entry end 168 and an exit end 169. Each guide path165, 167 is adapted to receive a respective one of the two marginal sideportions 53 of the strip 50 at the entry end 168. More particularly, thetwo longitudinal marginal side portions 53 pass along the guide paths165, 167 from the entry end 168 to the exit end 169 as the strip 50advances along the second path 112 at the assembly station 106. The twoguide paths 165, 167 each comprise a respective longitudinal slot 171having one longitudinal side 173 open and the other longitudinal side175 closed. The two slots 171 are disposed one adjacent the other and inopposed relation, whereby each slot configured to receive a respectiveone of the two longitudinal marginal side portions 53 for slidingmovement therealong when in overlapping relation. The two longitudinalmarginal side portions 53 are received in the guide paths 165, 167, withthe free edge of each longitudinal marginal side portion 109 in abuttingthe closed side 175 of the respective slot 171. In this way, theoverlapping longitudinal marginal side portions 53 can be correctlyaligned one with respect to the other for affixing together upon leavingthe guide 163 at the exit ends 169 of the guide paths 165, 167.

The assembly apparatus 100 further comprises a guidance system 181 forguiding the strip 50 for maintaining the two longitudinal marginal sideportions 53 in correct alignment with the guide 163; that is, tomaintain the two longitudinal marginal side portions 53 correctlypositioned within the guide paths 165, 167 defined by the opposed slots171 within the guide 163.

The guidance system 181 comprise at least one steering device 183 ininteracting with the strip 50 adjacent each longitudinal marginal sideportion 53, as shown in FIGS. 21 to 24. The guidance system 181 isprovided at the steering station 102. The steering station 102 comprisestwo sections 102 a and 102 b, each associated with one of the twolongitudinal marginal side portions 53 of the strip 50. With thisarrangement, at least one steering device 183 is provided at each of thetwo sections 102 a, 102 b of the steering station 102.

Each steering device 183 is operable to interact with the respectivelongitudinal marginal side portion 53 in a manner which either (a)enables the longitudinal marginal side portion to continue to travelalong its current path when in the correct alignment or (b) causes thelongitudinal marginal side portion 53 to shift laterally when there issome misalignment and correction is required. In the event that thelongitudinal marginal side portions 53 are not correctly aligned toestablish the required overlap therebetween, positional adjustments canthus be made to either one or both of them as necessary to correct themisalignment. The misalignment may, for example, result in either one orboth of the longitudinal marginal side portions 53 are not being incorrect alignment with guide 163 such that the free edge of thelongitudinal marginal side portion 109 is not positioned to slidinglyabut the closed side 175 of the respective slot 171 as required.

Each steering device 183 is operable to interact frictionally with therespective longitudinal marginal side portion 53 to effectively steerthe longitudinal marginal side portion 53 as it moves past the guidedevice.

More particularly, each steering device 183 comprises a steerableelement 185 which presents a line of action 186 at the interface withthe respective longitudinal marginal side portion 53, as depictedschematically in FIGS. 22, 23 and 24. In circumstances where the line ofaction 186 of the steerable element 185 is aligned with the direction oftravel of the longitudinal marginal side portion 53, the steering device183 has not effect on the travel of the longitudinal marginal sideportion. If, however, the line of action 186 of the steerable element185 is varied (by a steering action imposed upon the steerable element)such that it is angled to the direction of travel of the longitudinalmarginal side portion 53, the steering device 183 has a correctiveeffect on the direction of travel of the longitudinal marginal sideportion. In effect, the steering device 183 has a steering effect on theadvancing the longitudinal marginal side portion, causing thelongitudinal marginal side portion 53 to shift laterally when correctionis required.

In the arrangement shown in FIGS. 21 to 24, each steering device 183comprises a steerable element 185 in the form of a guide wheel 185having a rolling axis 187 (axis of rotation) and also a steering axis189. The steering axis 189 is normal to the rolling axis 187 and alsonormal to the path of travel of the respective longitudinal marginalside portion 53 as the latter slides upon the wall surface 141 of theplate structure 121. With this arrangement, the steering axis 189 isalso normal to the plane of wall surface 141 of the plate structure 121.The guide wheel 185 presents a rolling surface 191 which contacts theadvancing longitudinal marginal side portion 53. The line of action 186of the guide wheel 185 is at the interface between the rolling surface191 and the advancing longitudinal marginal side portion 53, tangentialto the rolling surface 191 and normal to the rolling axis 187.

The guide wheels 185 mounted on a chassis 192 above the plate structure121.

The guide wheels 185 are each rotatable about a respective rolling axis187, with the rolling axis being normal to the direction of travel ofthe respective longitudinal marginal side portion 109 along the guidepaths 165, 167 when they are correctly aligned. The guide wheels 185 arealso each steerable about steering axis 189 normal to both the rollingaxis 187 of the respective guide wheel and the direction of travel ofthe two longitudinal marginal side portions 109 along the guide paths165, 167 when they are correctly aligned.

If either one (or both) of the two longitudinal marginal side portions53 moves out of the correct alignment, and corrective action is therebyrequired, the guide wheel(s) 185 associated with the particularlongitudinal marginal side portion 53 requiring correction can berotated about the steering axis 189 to vary the angle of its respectiverolling axis 187 (and hence the line of action 186) with respect to thedirection of travel of the particular longitudinal marginal side portion53 With this arrangement, the steered guide wheel 185 interacts with themoving longitudinal marginal side portion 53 with which it is incontact, with reaction forces therebetween causing lateral displacementof the longitudinal marginal side portion 53 and thereby correcting themisalignment.

Operation of the guidance system 181 is depicted schematically in FIGS.25, 26 and 27. FIG. 22 depicts a condition in which the line of action186 of the steerable element 185 (the guide wheel) is aligned with thedirection of travel of the longitudinal marginal side portion 53. Inthis condition, the steering device 183 has not effect on the travel ofthe longitudinal marginal side portion; that is, the longitudinalmarginal side portion 53 continues to travel in a direction aligned withthe line of action 186 of the steerable element 185. FIG. 23 depicts acondition in which travel of the longitudinal marginal side portion 53requires correction. In order to provide the correction, the steerableelement 185 (the guide wheel) is rotated about its steering axis 189such that the line of action 186 is angled to the direction of travel ofthe longitudinal marginal side portion 53. When so angled, the steeringdevice 183 has a corrective effect on the direction of travel of thelongitudinal marginal side portion. In effect, the steerable element 185has a steering effect on the advancing longitudinal marginal sideportion, causing the longitudinal marginal side portion 53 to shiftlaterally in the required direction as determined by the angulardisposition of the line of action 186. The longitudinal marginal sideportion 53 shifts laterally by sliding upon the wall surface 144 ofplate structure 121 under the influence of the steerable element 185.FIG. 24 is a view similar to FIG. 23, but depicting correction in theother direction.

In FIGS. 23 and 24, arrows identified by reference character C depictthe lateral shift which the longitudinal marginal side portion 53undergoes under the influence of the steerable element 185.

Steering is provided by way of steering motors 195 mounted on thechassis 192 and operatively coupled to the steerable elements 185. Thesteering motors 195 may comprise servo motors or linear motors. Thesteering motors 195 may be operatively connected to the respective guidewheel(s) 185 by steering control rods 197. Steering is controlled bycontrol system 107.

In this embodiment, the guide wheels 185 are freely rotatable. In otherwords, the guide wheels 185 rotate merely through interaction with thestrip 50 as the two longitudinal marginal side portions 53 travel alongthe guide paths 165, 167; that is, they are not otherwise powered. Inanother arrangement, the guide wheels 185 may be powered, and therebyoperable to impose traction and/or drag on the strip 50. In yet anotherarrangement, the guide wheels 185 may have a braking or retardationfeature for imposing drag on the strip 50.

The steerable elements 185 need not necessarily be in the form of guidewheels, and other arrangements are contemplated. By way of example, thesteerable elements 185 may be in the form of rollers (including inparticular elongate rollers), and other forms of cyclically movableelements such as endless track mechanisms. Further, the steerableelements 185 need not necessarily be in the form of cyclically movableelements such as wheels, rollers and endless track mechanisms. Thesteerable elements 185 may, for example, be configured as skids insliding contact with the strip 50 as the two longitudinal marginal sideportions 53 travel along the guide paths 165, 167. The skids would eachpresent a line of action 186, typically aligned with a longitudinal axisof the skid. Further, the skids would each be rotatable about a steeringaxis for varying the alignment of the line of action (e.g. thelongitudinal axis of the skid) to effect a steering action as previouslydescribed.

The guidance system 181 further comprises a monitoring system 201 formonitoring travel of the strip 50 through the assembly station 106. Moreparticularly, the monitoring system 201 is operable to track the travelof the two longitudinal marginal side portions 53 in assuming theoverlapping condition that is required for affixing them together. Inthis embodiment, the monitoring system 201 is operable to track travelof the two longitudinal marginal side portions 53 relative to thealignment device 161. In the event of an out-of-alignment conditionbeing detected, the monitoring system 201 is operable to initiateremedial action; for example, through initiating operation of thesteering facility for the guide wheels 185 via the control system 107.Operation of the steering facility is initiated though operation ofeither one or both of the steering motors 195, as necessary.

The monitoring system 201 is provided at the monitoring station 103. Themonitoring station 103 comprises two sections 103 a, 103 b, eachassociated with one of the two longitudinal marginal side portions 53 ofthe strip 50. With this arrangement, the two longitudinal marginal sideportions 53 of the strip 50 are monitored individually

In this embodiment, the monitoring system 201 comprises an opticaltracking system 203, although of course other tracking systems may bedeployed (such as, for example, a tactile tracking system). The opticaltracking system 203 comprises two optical sensors 205 such as cameras,one at each section 103 a, 103 b of the monitoring station 103. Eachoptical sensor 205 is operable to track a feature of the strip 50indicative of the alignment of the respective longitudinal marginal sideportion 53 In this embodiment the feature of the strip 503 being trackedis a marking 207, such as a line, applied to the strip 50. With thisarrangement, there may be two markings 207 (e.g. lines) applied to thestrip 50, one on or adjacent each longitudinal marginal side portion 53.The markings 207 (lines) may applied to the strip 50 in any appropriateway; for example, during production of the web 115 which provides thestrip, during winding of the web onto a storage reel, or during travelof the web 115 along the second path 112 to the assembly station 101. Inthis embodiment, the two marking 207 are applied as lines to the web 115by a printing process. More particularly, the lines are applied by twoprinters (not shown), each operable to print a continuous line onto thestrip 50 along or adjacent a respective one of the longitudinal marginalside portions 53. The printed lines extend parallel to the adjacentlongitudinal side edges of the strip 53. The markings 207 may of coursetake other forms. Further, the markings 207 may be applied in ways otherthan printing.

A variation of the guidance system 291 is depicted schematically in FIG.33. In the illustrated arrangement there are steerable elements 185 apositioned for interaction with the strip 50 while the longitudinalmarginal side portion 53 are in an overlapping condition but prior tobonding. The steerable elements 185 a may be additional to, or areplacement for, the steerable elements described previously in relationto FIGS. 21 to 24. The steerable elements 185 a operate under thecontrol of control system 107 in the same way as steerable elements 185.

While in the arrangements shown there is only one steerable element (185or 185 a) associated with each longitudinal marginal side portion 53,there may of course be a plurality of steerable elements associated witheach longitudinal marginal side portion. In such a case the steerableelements associated with each longitudinal marginal side portion 53 mayoperate in tandem.

The overlapping station 104 and the bonding station 105, are integratedwith the assembly station 106 station 105. The operations performed atthe overlapping station 104 and the bonding station 105 are aspreviously described to complete assembly of the inner layer 41 a aboutthe inner tube 30.

Once the innermost layer 41 a has been wrapped about the tube 30 aspreviously described, the second layer 41 b can then be wrapped aboutthe innermost layer 41 a This is followed by wrapping of a third layer41 c about the second layer 41 b. The process is repeated until allrequired layers 41 are in position. Additionally, if infusion media isto be provided, the infusion media layer 43 is wrapped about previouslyinstalled concentric layers 41.

As stated above, the production of the prefabricated tubular assembly 24may involve various passes of the tubular assembly 24 under constructionthrough the apparatus 100, with each pass installing the next layer.Alternatively, the apparatus 100 may have a plurality of stations inseries, with each station installing a respective one of the variouslayers, preferably at different orientations around the circumference ofthe tubular assembly.

From the foregoing, it is notable that the inner tube 30 and theinnermost layer 41 a of reinforcing fabric immediately surrounding theinner tube, can be considered as a tubular assembly comprising an innerportion and a further portion surrounding the inner portion, with theinner tube 30 constituting the inner portion and the innermost layer 41a of reinforcing fabric constituting the further portion surrounding theinner portion. For the purposes of further description, the tubularassembly comprising the inner tube 30 and the innermost layer 41 a willhereinafter be referred to as the first tubular assembly.

The next innermost layer 41 b could be considered to be surrounding thefirst tubular assembly. Accordingly, said next innermost layer 41 b andsaid first tubular assembly, can be considered as a tubular assemblycomprising an inner portion and a further portion surrounding the innerportion, with said first tubular assembly constituting the inner portionand the next innermost layer 41 b constituting the further portionsurrounding the inner portion.

Accordingly, any one layer 41 (together with any preceding layers 41 andthe inner tube 30) may constitute said inner portion, and another layersurrounding said one layer may constitute said further portion.

Referring now to FIGS. 26, 26 and 28, there is shown a mobile facility200 for construction and laying of pipeline 10. The mobile facility 200comprises a vehicle 201 adapted to travel along a site at which thepipeline 10 is being produced and laid. In the arrangement shownschematically in FIG. 26, the vehicle 201 comprises a prime mover 203and a load carrying portion 205 configured to receive apparatus,equipment and supplies used in the pipe production process. I

Included on the load carrying portion 205 is compression apparatus 207for compression of the assembled tubular structure 40 to close the innertube 30, as described earlier. The compression apparatus 207 maycomprise apparatus disclosed in the Applicant's internationalapplication PCT/AU2015/000332, the contents of which are incorporatedherein by way of reference.

In the arrangement shown, there is provided a container 211accommodating a supply of prefabricated tubular assemblies 24. Thesupply comprises a plurality of lengths of the prefabricated tubularassembly 24, each folded into a compact condition from which it can bedeployed as required. The lengths of the prefabricated tubular assembly24 can each be progressively withdrawn from the container 211 asrequired during the pipe construction process. When the supply ofprefabricated tubular assemblies 24 requires replenishment, the existingcontainer 211 can be removed from the load carrying portion 205 of thevehicle 201 and substituted with a replacement container accommodating anew supply of prefabricated tubular assemblies 24.

Further, there is provided a supply of material which provides theflexible outer casing 23. In the arrangement shown, the supply is inroll form 213 and comprises a web or ribbon of strip material wound upona reel 215.

Still further, there is provided a supply of resinous binder used in theprocess to integrate the two portions 21, 22, the supply of resinousbinder being accommodated in reservoir 217.

Still further, there is provided an assembly station 220 at which theflexible outer casing 23 is installed around the prefabricated tubularassembly 24, and resinous binder is introduced into the reinforcement 37of the prefabricated tubular assembly 24, with the resinous binder beingcontained by the installed outer casing 23.

Still further, there is provided the previously described compressionapparatus 207. The compression apparatus 207 is positioned at oradjacent the end of the load carrying portion 205 of the mobile facility200.

FIG. 27 depicts, schematically, inflation of the assembled tubularstructure 40 through delivery of inflation fluid such as air by way ofblower or compressor 223 at the distal end of the tubular structure. Theinner tube 30 of the assembled tubular structure 40 is closed by thecompression apparatus 207 on the mobile facility 200. The compressionapparatus 207 is positioned at or adjacent the end of the load carryingportion 205 of the mobile facility such that the assembled tubularstructure 40 can “snake” downwardly from the mobile facility and ontothe ground over which the mobile facility is travelling as the pipe 20is progressively produced. The compression apparatus 207 advances withthe mobile facility 200. In FIG. 27, the assembled tubular structure 40is shown in an inflated condition behind the advancing compressionapparatus 207 and in an un-inflated condition ahead of the advancingcompression apparatus 207.

FIG. 28 depicts, schematically, inflation of the assembled tubularstructure 40 and movement of resinous binder through reinforcement 37within the tubular structure. As the assembled tubular structure 40 isprogressively inflated and the space in which the reinforcement 37 isconfined progressively decreases, the resinous binder is forced throughthe layers 41 of reinforcing fabric for distribution within the space ina controlled and constrained manner. The resinous binder is caused tomove through the layers 41 of reinforcing fabric within the space as aprogressively rising resin pool or wave as a consequence of theprogressively decreasing volume of the space. The progressively risingresin pool is shown schematically in FIG. 28, with the notional surfaceof the progressively rising resin pool being identified by referencenumeral 224. Vents 225 are provided in the outer casing 23 to facilitateexpulsion of the air from space are also shown. The vents 225 maycomprise perforations formed by a perforating mechanism provided as partof the mobile facility 200.

At the assembly station 220, the flexible outer casing 23 is installedaround the prefabricated tubular assembly 24, and resinous binder isintroduced into the reinforcement 37 of the prefabricated tubularassembly 24, with the resinous binder being contained by the installedouter casing 23.

FIG. 29 is a schematic view depicting various operations performed toinstall the flexible outer casing 23 around the prefabricated tubularassembly 24 to provide the assembled tubular structure 40, with resinousbinder being introduced into the reinforcement 37 of the prefabricatedtubular assembly 24, and the assembled tubular structure 40 subsequentlybeing inflated. The step involving inflation of the assembled tubularstructure 40 is identified in FIG. 29 by reference numeral 230.Inflation of the assembled tubular structure 40 brings the inner tube 30into direct contact with the reinforcement 37, and also brings thereinforcement 37 into direct contact with the outer casing 23.

The prefabricated tubular assembly 24 advances from the container 211 tothe assembly station 220 along a first path 231.

The outer casing 23 is formed from a strip 233 in the form of the web235 unwinding from reel 237. The strip 233 advances from the reel 237 tothe assembly station 220 along a second path 232.

The strip 233 comprises a central longitudinal portion 241 and twolongitudinal marginal side portions 242 on opposed sides of the centrallongitudinal portion. Each longitudinal marginal side portion 242 has alongitudinal edge 243. The strip 237 is typically of unitaryconstruction, with the central longitudinal portion 241 and twolongitudinal marginal side portions 242 being zones of the unitary stripidentified for reference purposes, rather than being distinct orseparate parts. However, the strip 233 need not necessarily be ofunitary constriction, and the central longitudinal portion 241 and twolongitudinal marginal side portions 242 may alternatively comprisedistinct or separate parts joined together.

The strip 233 is wrapped around the prefabricated tubular assembly 24 atthe assembly station 220, with the two marginal side portions 242disposed in overlapping relation and affixed together to assemble thestrip into a tubular configuration providing the outer casing 23 aboutthe prefabricated tubular assembly 24, as will be explained in moredetail later. This comprises a garniture wrapping step identified inFigure X by reference numeral 244

The two marginal side portions 242 of the strip 233 are affixed togetherto provide a longitudinal lap seam 245. The two marginal side portions242 of the strip 233 are affixed together in a manner to provide arobust or permanent seam which does not release or lose integrity uponradial expansion of the casing 23. In other words, and in contrast tothe longitudinal lap seams 55 of the layers 41 within the prefabricatedtubular assembly 24, longitudinal lap seam 245 is not constructed tofacilitate slippage between the two marginal side portions in the seam.Rather, it unyieldingly locks the two marginal side portions 253together at the seam 245 the seam

In advancing from the reel 237 to the assembly station 220 along thesecond path 232, the web 235 providing the strip 233 is progressivelyfolded upon itself from a flat condition into a tubular configurationwith the two longitudinal marginal side portions 109 in overlappingrelation. This is somewhat similar to the manner in which strips 50 werefolded to provide the layers 41, 42 in the layers of the prefabricatedtubular assembly 24. Similarly, various guide elements are providedalong the path 232 of movement of the strip 233 for progressivelycausing the strip to assume the tubular configuration with the twolongitudinal marginal side portions 242 in overlapping relation. Theguide elements include turn elements about which the web 235 is turnedfor directional control, and profiling elements for causing the web tofold longitudinally to progressing urge the central longitudinal portion241 to assume an arcuate profile and move the two longitudinal marginalside portions 242 inwardly towards each other.

The assembly station 222 comprises a plate structure 251 defining a wall253. In the arrangement shown, the first path 231 passes below the wall253 and the second path 232 surrounds the wall.

The assembly station 220 further comprises a base portion 255 mountedbelow the plate structure 251. In the arrangement shown, the baseportion 255 is suspended from the plate structure 251 at the edgesproviding connections 257.

The base portion 255 and the plate structure 251 cooperate to define aspace 259 through which the first path 231 extends. With thisarrangement, the prefabricated tubular assembly 24 passes through thespace 259, as shown in FIG. 29.

As the prefabricated tubular assembly 24 passes through the space 259,the strip 233 is wrapped around the prefabricated tubular assembly 24 toform the outer casing 23. More particularly, the strip 233 progressivelyassumes the tubular configuration as it approaches the assembly station220. Upon arrival of the strip 233 at the assembly station 220, thetubular configuration encircles the base portion 255 and the platestructure 251, and thus also the prefabricated tubular assembly 24passing through the space 259, as best seen in FIG. 31. With thisarrangement, the outer casing 23 is installed completely about theprefabricated tubular assembly 24 upon the prefabricated tubularassembly 24 exiting from the space 259, thereby completing the assembledtubular structure 40.

The assembly station 220 further comprises a system 261 for affixing thetwo longitudinal marginal side portions 242 together in overlappingrelation to complete assembly of the strip 233 into a tubularconfiguration to provide the outer casing 23 about the prefabricatedtubular assembly 24.

The affixing system 261 for affixing the two longitudinal marginal sideportions 242 together in overlapping relation may take any appropriateform. In the arrangement shown, the affixing system 261 comprises a heatwelding apparatus 263, comprising a probe 265 for delivering hot airinto a gap between the overlapping longitudinal marginal side portions242. Subsequent closing of the gap by pressing the two longitudinalmarginal side portions 242 together establishes bonding therebetween byway of a plastic weld.

The affixing system 261 further comprises a press 267 for pressing thetwo portions 242 into contact one with the other to establish bondingtherebetween by way of the plastic weld, as described above. This may befollowed by a cooling blast of air to cool or chill the weld tofacilitate maximum strength of the welded joint quickly before it comesunder inflation loads as it exits the affixing system 261. The wall 253at the assembly station 220 presents a wall surface 269, and the press267 is provided for pressing the two longitudinal marginal side portions242 together against the wall surface. 269. The wall 269 may be heated.In the arrangement shown, the press 267 comprises a press roller system,with the overlapping marginal side portions 242 passing between thepress roller system and the wall surface 269.

The affixing system 261 may be mounted on a lateral rail system,permitting selective positional adjustment, or any rapid introduction orremoval of a heat source, as may be required.

The assembly station 220 further comprises an alignment system 281 foraligning the two longitudinal marginal side portions 242 in overlappingrelation prior to being affixed together.

The alignment system 281 comprises a guide 283 mounted on the platestructure 251. The alignment system 281 is somewhat similar inconstruction and operation to the alignment system 151 describedpreviously in relation to construction of the prefabricated tubularassembly 24, and as such will not be described in any further detail.

The assembly station 220 further comprises a guidance system 291 forguiding the strip 233 for maintaining the two longitudinal marginal sideportions 242 in correct alignment with the guide 283; that is, tomaintain the two longitudinal marginal side portions 242 correctlypositioned within the guide paths defined by the opposed slots withinthe guide 283.

The guidance system 291 is somewhat similar in construction andoperation to the guidance system 181 described previously, and as suchwill not be described in any further detail. It should however be notedthat the guidance system 291 includes steerable elements 293 operable ina manner similar to that discussed in relation to steerable elements183.

Steering is provided by way of steering motors 295 mounted on thechassis 297 and operatively coupled to the steerable elements 293.

The guidance system 291 further comprises a monitoring system 301 formonitoring travel of the strip 233 through the assembly station 220.More particularly, the monitoring system 301 is operable to track travelof the two longitudinal marginal side portions 242 in assuming theoverlapping condition that is required for affixing them together. Inthis embodiment, the monitoring system 301 is operable to track travelof the two longitudinal marginal side portions 242 relative to thealignment system 281. In the event of an out-of-alignment conditionbeing detected, the monitoring system 301 is operable to initiateremedial action; for example, through initiating operation of thesteering facility for the steerable elements 293. Operation of thesteering facility is initiated though operation of either one or both ofthe steering motors 295, as necessary.

The monitoring system 301 is somewhat similar in construction andoperation to the monitoring 181 described previously, and as such willnot be described in any further detail. It should however be noted thatthe monitoring system 301 includes optical tracking operable in a mannersimilar to that discussed previously.

The monitoring system 301 features optical tracking, as discussedpreviously, although of course other tracking systems may be deployed.

As was the case previously, the optical tracking system 311 is operableto track a feature of the strip 233 indicative of the alignment of therespective longitudinal marginal side portion 242. In this case thefeature of the strip 233 being tracked is the periphery of the strip;specifically, each longitudinal edge 243 of the strip. Tracking thelongitudinal edges 243 of the strip 233 is feasible in this instancebecause the strip has straight edges owing to the material from which itis made and the manner in which it is made or accurately cut to size.This is in contrast to the longitudinal edge of the strips 50 whichprovide the layers 41 of the prefabricated tubular assembly 24 which areof woven fibre construction and as such do not feature clean or clearedges which are appropriate as a basis for reliable tracking.

As mentioned above, the monitoring system 301 includes optical trackingoperable, although other tracking systems may be deployed. For instance,tracking may be by way of a positional sensing system interacting witheach longitudinal edge 243 of the strip 233. The positional sensingsystem may have tactile sensors such as micro-switches interacting withthe longitudinal edges 243 of the strip 233.

Operations at the guidance system 291 further comprises a monitoringsystem 301 may be under the control of a control system 315 such as acomputer control system. The control system 315 may also control otheroperations conducted at the assembly station 220.

The assembly station 220 further comprises a system 321 for delivery ofresinous binder to the reinforcement 37 of the prefabricated tubularassembly 24 as the latter passes through the space 259, as shown inFIGS. 31 and 31. The resinous binder is delivered along a supply line323 extending from the reservoir 217 to a delivery port 325 opening ontothe space 259 through the base portion 255 which defines a surface 256over which the prefabricated tubular assembly 24 moves. In thearrangement shown, the delivery port 325 is of elongate configuration.There may be more than one delivery port 325 in other embodiments, ifdesired.

The surface 256 is configured to direct the injected resin binderupwardly and outwardly through the annular section defined between theinner tube 30 and outer casing 23 in which the reinforcement 37 isconfined. In the arrangement shown, the surface is concave.

The surface 256 may be configured in any other appropriate way fordelivery of resinous binder into the reinforcement 39; for example thesurface 256 may comprise channels through which the resin binder isdelivered

With this arrangement, resin binder is injected into the bottom of thespace 259 for exposure to the infusion media layer 43 and the associatedreinforcing fabric tubular layers 41 of the prefabricated tubularassembly 24 as the latter passes through the space 259.

The outer casing 23 is installed completely about the prefabricatedtubular assembly 24 upon the prefabricated tubular assembly 24 exitingfrom the space 259, and so the resinous binder so introduced iscontained within the assembled tubular structure 40 by the outer casing23.

The resinous binder is subsequently caused to move through theconcentric reinforcing fabric tubular layers 41 and the infusion layer43 within the assembled tubular structure 40 as a progressively risingresin pool or wave (as a consequence of the progressively decreasingvolume of the space between the expanding inner tube 30 and the flexibleouter casing 23), as previously described.

A variation of the guidance system 291 is depicted schematically in FIG.33. In the illustrated arrangement, there are steerable elements 293 apositioned for interaction with the strip 233 while the longitudinalmarginal side portions 242 are in an overlapping condition but prior tobonding. The steerable elements 293 a may be additional to, or areplacement for, the steerable elements described previously. Thesteerable elements 293 a operate under the control of control system 315in the same way as steerable elements 293.

From the foregoing, it is evident that the assembled tubular structure40 can be considered as a tubular assembly comprising an inner portionand a further portion surrounding the inner portion, with theprefabricated tubular assembly 24 constituting the inner portion and theflexible outer casing 23 constituting the further portion surroundingthe inner portion.

It should be appreciated that the scope of the invention is not limitedto the scope of the embodiment described. Those skilled in the art willappreciate that the invention described herein is susceptible tovariations and modifications other than those specifically described.The invention includes all such variation and modifications. Theinvention also includes all of the steps, features, formulations andcompounds referred to or indicated in the specification, individually orcollectively and any and all combinations or any two or more of thesteps or features.

Modifications and variations such as would be apparent to the skilledaddressee are considered to fall within the scope of the presentinvention.

The present disclosure is provided to explain in an enabling fashion thebest modes of making and using various embodiments in accordance withthe present invention. The disclosure is further offered to enhance anunderstanding and appreciation for the invention principles andadvantages thereof, rather than to limit in any manner the invention.While a preferred embodiment of the invention has been described andillustrated, it is clear that the invention is not so limited. Numerousmodifications, changes, variations, substitutions, and equivalents willoccur to those skilled in the art having the benefit of this disclosurewithout departing from the spirit and scope of the present invention asdefined by the following claims.

Reference to positional descriptions, such as “inner”, “outer”, “upper”,“lower”, “top” and “bottom”, are to be taken in context of theembodiments depicted in the drawings, and are not to be taken aslimiting the invention to the literal interpretation of the term butrather as would be understood by the skilled addressee.

Additionally, where the terms “system”, “device”, and “apparatus” areused in the context of the invention, they are to be understood asincluding reference to any group of functionally related or interacting,interrelated, interdependent or associated

Throughout this specification, unless the context requires otherwise,the word “comprise” or variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated integer or groupof integers but not the exclusion of any other integer or group ofintegers.

1.-7. (canceled)
 8. Apparatus for constructing a tubular assemblycomprising an inner portion and a further portion surrounding the innerportion, the inner portion comprising reinforcement and the furtherportion being formed from a strip of material comprising two opposedlongitudinal marginal side portions; the apparatus comprising: anassembly station comprising a wall; means for advancing the innerportion along a first path extending passed the wall; means foradvancing the strip along a second path and causing the strip toencircle the wall and thereby wrap about and surround the inner portion,a surface over which the prefabricated tubular assembly is caused tomove; means for introducing resinous binder into the reinforcement asthe strip is being wrapped about the inner portion; wherein the surfacehas a least one port through which the resinous binder is delivered tothe reinforcement wherein the wall is defined by a plate structure andthe surface is defined by a base portion mounted below the platestructure; wherein the base portion and the plate structure define aspace through which the first path extends; and wherein the base portionis suspended from the plate structure. 9.-17. (canceled)